This subproject is one of many research subprojects utilizing the resources provided by a Center grant funded by NIH/NCRR. The subproject and investigator (PI) may have received primary funding from another NIH source, and thus could be represented in other CRISP entries. The institution listed is for the Center, which is not necessarily the institution for the investigator. Mesenchymal stem/progenitor cells (MSC) are a population of adherent bone marrow mesenchymal cells with the ability to proliferate beyond the Hayflick limit and differentiate into multiple mesenchymal lineages. However, studies indicate that MSC are highly heterogeneous and clonal assays are needed to fully evaluate their potential usefulness for tissue regeneration and repair.